Radio receiving circuit



Aug.- 7, 192& .1,619,597

T. H. BERKLAND RADIO RECEIVING CIRCUIT Filed' .July 1s, 1925 7 4 fZ S P5 1.1: VEL-11E?? Patented Aug. 7, v192s.

` THOMAS H. BERKIAND, or cHIcAGo, ILLINOIS.

- RADIO RECEIVING CIRCUIT.

Application led July 13, 1925. Serial No. 43,115. y v

i a maximum of selectivity and clearness of reception.

Other and further important objects of this invention will be apparentfrom the disclosures in the specification and the accompanying drawings.v

This invention (in. a preferred form) is illustrated in the drawings andhereinafter more fully described.

On the drawings: l

The figure of they drawings represents a diagrammatic sketch of `acircuitlembodying the principles of this invention.

As shown on the drawings: v

An antenna 1 is connected to the primary 2 of a' radio frequencytransformer having a Variable condenser 3 inseries with said primary andantenna. There is connected to the variable condenser 3 opposite to saidprimary 2 one terminal of a secondary coil l and the grid of a vacuumtube 5. Connected to the other terminal of the secondary coil 4 is thenegative side of a C-battery 6.

A second vacuum tube 7 `is also provided, n

the filaments of the vacuum tubes 7 .and 5 being connected in parallelthrough their respective resistances across an A-battery 8. A B-battery9 is provided having sixtyseven volts across its extreme terminals 10and 11 respectively. An intermediate terminal 12 is provided on theB-battery 9 for,

providing a voltage of forty-five volts. A. second radio frequencytransformer is provided having a primary`13, a variable condenser 14connected to one end offsaid primary and a secondary 15 having oneendAconnected to said variable condenser 14 opposite said primary. The`other end of the secondary 15 is connected to the filaments of thevacuum tubes atvthe positive side ofy the A-battery 8. The other end ofthe prio mary 13 is connected to the positive side of the B-battery 9 atthe terminal 10. The

grid of the 'vaccum tube 7 is connected toV the variable condenser 14 onthe side opposite ytothe primary 13 through a grid condenser and l leak16. vThe plate kof the vacuumv tube 5 is Vconnected to the second lradio frequency transformer between .the`

kprimary y13 thereof and the variable condenser 14:.

The negative sides'of the fila-V ments of the vacuum tubes 7 and 5 areVconnectedto the negative side of the iA-battery 8 and also to thenegativeterminal 11 of the B-battery 9. The negative terminal `11 of theBbattery 9 is also connected to the positive side of the C-battery 6.The plate of the vacuum tube `7 is connected to the intermediateforty-ivejvolt terminal 12 of the B-batteryv 9 througha pairofphones-17, or like instrument, such as a loud speaker. The negativeterminals of the A and B-batteries and the positive terminal of theC-battery are connected to ground'at 18 through a suitable conductor 19as shown.A

It will be apparent that the above arrangement permits the tuning of theinput and output circuits simultaneously, and that by balancing theradio frequency and audio frequency circuits, as herein disclosed, amaximum of selection and clearness of reception is' obtained.

I am aware that many changes may be made'yand numerous details ofconstruction maybe varied throughl a wide range without departing fromthe principles ofthis'invention,l and I ytherefore dov not pu oselimiting'the patent granted hercon, ot er wise thanY necessitated by theprior art.

I'claim as my invention: I

ycapacitively rconnected to the gridv of said tube throughv a variablecondenser other end.

2. Ina radio receiving system, a ther-v ymionic tube, the primary of aradio frequency transformer, the secondary of said radio frequencytransformer, said secondary conductively connected to thegrid of said atthe es,l

tube at one end and to the negative pole of the filament heating batteryat the other end7 the primary of said transformer concluctvely connectedto the positive pole of a 5 plate potential Qontrol battery at one endandV eapaetiyely connected to the grid of said tube through a. variablecondenser at the other end, and a conductive connection with the plateof another' thermonle tube at the enel of said primary at which it con-THOMAS H. BERKLAND. v

